This invention pertains to an object inspection system, and more particularly to such a system which enables the simple simultaneous inspection of the condition of opposite sides of a selected object.
There are various types of operations wherein it is necessary to inspect the opposite sides of an object in order to make a proper judgment as how next best to process the object. For example, in the manufacture of furniture, it is necessary to inspect the opposite sides of lumber pieces to determine the total lateral spreads of knots and other defects in such pieces so as to be able to determine how best to cut the lumber, with minimum waste, into the finally desired furniture piece shapes. Heretofore, it has been necessary first to inspect one side of such a lumber piece, and then to turn the piece over, usually manually, to examine the corresponding opposite side of the piece, thus to gauge the overall spread of a defect in the piece. Such a practice is obviously quite time consuming and expensive.
A general object of the present invention is to provide a unique inspection system for inspecting the opposite sides of an object, such as a piece of lumber, which system avoids in a practical and satisfactory manner the above-mentioned deficiencies of conventional inspection techniques.
More particularly, an object of the invention is to provide such a system which enables the ready and simple simultaneous inspection of opposite sides of an object, thus to enable instantaneous noting of the total lateral spread of a defect, such as a knot, in the object.
According to a preferred embodiment of the invention, an inspection system is proposed including apparatus for projecting onto a selected portion of one side of an object in a viewing station a positionally aligned, unidirectionally reversed image of the corresponding portion of the opposite side of the object. Such apparatus employs a pair of viewing and projection mirrors which are arranged to confront such opposite sides of an object in the station, with these two mirrors cooperating with an image-reversing mirror which is located outside the viewing station. In one embodiment of the invention, a single imaging lens is employed in the optical path which extends between the two viewing and projection mirrors. In a modification, a pair of such lenses are used, these two lenses being coaxial and relatively adjustable to change the spacing therebetween. As will be explained, this modification enables adjustment of the apparatus properly to handle objects of different thicknesses.
With an object which is to be inspected in the viewing station, one side of the object is lighted, and the apparatus of the invention then projects a full-scale image of this side onto the other side of the object where it may be viewed simultaneously with such other side. The image-reversing mirror assures proper orientation of the projected image.
With such projection, it will be obvious that it is an extremely simple matter for an operator to view a single side of an object onto which has been projected the image of the opposite side, and to see clearly the total lateral extent of any defect, such as a knot, which may extend completely through the object.
It will further be appreciated that the proposed system, in both of its embodiments, as generally outlined above, is extremely simple in construction, can easily be used, and can readily be incorporated in various kinds of equipment.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description thereof which now follows is read in conjunction with the accompanying drawings.